Wing Tip Research Articles

Three-Dimensional Modified Cross-Section Hydrofoil Design and Performance Study

To improve the hydrodynamic performance of hydrofoils, this study combines the shape characteristics of flat and elliptical wings, uses parabolic function to fit the leading and trailing edges of hydrofoils, introduces the cross-section coefficient λ to characterize the cross-sectional size of hydrofoils along the spreading direction, and designs five hydrofoils with different cross-sections. The motion of the hydrofoil is simulated using the finite element analysis software Fluent to obtain the hydrodynamic performance curve of the hydrofoil and analyze the effect of different end face sizes on the performance of the hydrofoil. The results show that compared with the flat wing, the peak drag of the variable section hydrofoil with λ = 0.5 is reduced by 9.3%, the pitching moment is reduced by 23.1%, and the average power is raised by 17.4%. If the appropriate reduction in the cross-section coefficient is too small, it will exacerbate the wing tip vortex shedding, the hydrofoil surface pressure will be too concentrated, and the hydrofoil motion stability will be reduced. The lift coefficient, drag coefficient, and pitching moment coefficient of the hydrofoil are positively correlated with the cross-section coefficient λ, and positively correlated with the motion frequency.

NOTCH Signaling Networks in Perivascular Adipose Tissue.

Over a hundred years ago, mutants were detected in Drosophila melanogaster that led to a NOTCH in the wing tip. This original phenotype was reflected in the nomenclature of the gene family that was later cloned and characterized in the 1980s and found to be conserved across metazoans. NOTCH signaling relies on transmembrane ligands and receptors that require cellular contact for receptor activation, reflecting its role in multicellular organisms as an intercellular signaling strategy. In humans, mutations in genes encoding NOTCH and their ligands have been shown to promote human disease; these aspects have been extensively reviewed. Notch signaling plays important roles in vascular development (vasculogenesis and angiogenesis) and homeostasis. NOTCH signaling is also active in adipose tissue and contributes to adipocyte differentiation. In addition, NOTCH activity regulates functions of other metabolic organs. This review focuses on NOTCH activity in perivascular adipose tissue within the vascular microenvironment as defined by mouse studies and summarizes expression and potential signaling of the NOTCH signaling network in human perivascular adipose tissue. Due to the strong activity of NOTCH in regulation of metabolic function, activation of the NOTCH network in specific cell types in perivascular adipose tissue has implications for signaling to the underlying blood vessel and control of vascular health and disease.

Syntheses and crystal structures of 4-benzyl-1-ethyl-1,2,4-triazolium bromide and its corresponding NHC complexes of rhodium and iridium.

The syntheses and crystal structures of a triazolium salt, 4-benzyl-1-ethyl-1,2,4-triazolium bromide, C11H14N3 +·Br- (2), and the corresponding N-heterocyclic carbene complexes, (4-benzyl-1-ethyl-1,2,4-triazol-5-yl-idene)chlorido-[(1,2,5,6-η)-cyclo-octa-1,5-diene]rhodium(I), [RhCl(C8H12)(C11H13N3)] (3), (4-benzyl-1-ethyl-1,2,4-triazol-5-yl-idene)[(1,2,5,6-η)-cyclo-octa-1,5-diene](tri-phenyl-phosphane)iridium(I) tetra-fluorido-borate, [Ir(C8H12)(C11H13N3)(C18H15P)]BF4 (5), and (4-benzyl-1-ethyl-1,2,4-triazol-5-yl-idene)[(1,2,5,6-η)-cyclo-octa-1,5-diene](tri-cyclo-hexyl-phosphane)iridium(I) tetra-fluorido-borate dicholoro-methane sesquisolvate, [Ir(C8H12)(C11H13N3)(C18H33P)]BF4·1.5CH2Cl2 (6), are presented. Complexes 2 and 6 crystallize in the monoclinic space group P21/c, complex 3 in the triclinic space group P1 and complex 5 in the triclinic space group P1 with two mol-ecules in the asymmetric unit. The three metal complexes 3, 5, and 6 have a distorted square-planar geometry around the metal ions. The N1-C1-N3 bond angle in the triazolium salt 2 is 107.1 (2)° and is observed in the range of 102.2 (3) to 103.8 (5)° in the NHC ligands in complexes 3, 5, and 6. The two substituent 'wing tips' in the NHC ligand (N-ethyl and N-benz-yl) are oriented in an anti-arrangement in compounds 2 and 3, a syn-arrangement in compound 6, and both syn and anti-arrangements in the two independent ion pairs in compound 5. All structures exhibit non-classical hydrogen-bonding inter-actions with the most acidic hydrogen atoms in complexes 2 and 3 playing critical roles in the orientations of structural units.

Design, Modeling, and Comprehensive Analysis for The Wing of an Aircraft

This study examines the design and analysis of a training aircraft wing. The methodology includes aerodynamic and stress analyses. Microsoft Excel is utilized for scaling. Aerodynamic forces, load distribution, and air foil comparison computations were performed by Xflr 5. Inventor was used for stress analysis, which yielded wing deflections, Von Mises stresses, and safety factors. AutoCAD was employed to draw wing parts. The proper design for the cross-sectional shape of the inner wing components was determined. The goal is to find the lightest cross-section, the placements and numbers of wing ribs, and calculate the wing's dimensions. The findings revealed that wing tip deflection did not exceed 0.02. The von Mises calculations also show that the chosen material meets the requisite safety factor. For I and U sections, the deflection, von Mises stresses, and safety factor were 46.52mm and 43.27mm, 219.3 MPa and 152.7MPa, and 1.25 and 1.8, respectively.

Numerical Study of the Effect of Winglets with Multiple Sweep Angles on Wind Turbine Blade Performance

A numerical study was conducted on winglet designs with multiple sweep angles for improving the performance of horizontal axis wind turbine (HAWT) blades, and their effect on reducing the wing tip vortex was investigated by CFD analysis. The effects of sweep angles were examined through NREL Phase VI turbine blades considering a wind speed range of 7 to 25 m/s. Numerical simulations were performed using RANS equations and the SST k–ω turbulence model. The interaction of the blade rotation and wind flow was modeled using a moving reference frame method. The numerical results were found to be in good agreement with the inferences drawn from the experiments for a baseline blade without a winglet, thereby validating the computational method. The investigations revealed that multi-swept winglets predicted a 14.6% torque increment, providing higher power output than single-swept winglets compared to the baseline blade at a wind speed of 15 m/s. Implementing multiple sweep angles in winglet design can improve the blade performance effectively without further increments in winglet length.

Icing Characteristics of a Wing Behind a Propeller Wake

Propeller-generated wakes create complex aerodynamic interactions that influence ice accretion on aircraft wings, consequently affecting aerodynamic performance. However, the effect of the propeller wake on wing icing characteristics is not well understood. This study clarifies the mechanisms and extent of propeller wake effects on wing icing by comparing the icing characteristics with and without the propeller wake. Three-dimensional quasi-unsteady simulations are employed to capture temporal changes in the droplet field and ice accretion rates caused by local and unsteady propeller wake flows. The computational results provide insights into the icing characteristics induced by aerodynamic interactions. Higher axial velocities enhance droplet impingement and heat convection on the wing. Upwash and downwash change the local effective attack angle, altering droplet impingement limits and the size and intensity of heat convection. The rotation of tip vortices creates droplet voids and dense regions, enhancing heat convection on the inside of the wing tip and leading to noticeable differences in ice formation. Consequently, ice shapes behind the propeller wake are up to 80% thicker and more irregular, leading to twice as severe degradation in aerodynamic performance of the non-wake-induced iced wing. This study highlights the need to consider propeller wake effects in wing icing analysis.

Body size and wing shape as predictors of the initial flight acceleration in bats of the Brazilian Atlantic Forest

Bat body size and some aspects of the wing shape are considered efficient indicators of bat flight performance. Here, we evaluated how body size and wing shape can be predictors of initial flight acceleration (0-10 meters) in 15 bat species (3 families) occurring in the Atlantic Forest. Two body size variables (wingspan and body mass) and three wing shape variables (relative wing loading, aspect ratio and wing tip index) were taken from 74 individuals. We carried out flight experiments with another 59 individuals, to evaluate the Initial Flight Acceleration (IFA). We used generalized linear models (GLM) to evaluate which variables were the best predictors of initial flight acceleration. Furthermore, we tested the phylogenetic signal for initial flight acceleration, and the hypothesis of phylogenetic autocorrelation for this behavior was discarded (p > 0.05). Our results show that larger species with narrow wings need to develop greatest initial accelerations to take off flight. We suggest a morphological restriction on flight, since most bat species analyzed have low values in both variables and those that have high values are only in one of these variables.

Aerodynamic characteristics of a wing-in-ground effect with micro-vortex generators

Micro-vortex generators (MVGs) are simple passive flow control devices mounted on the base surfaces to mitigate the boundary layer flow separation. The effect of the MVGs installed on the aircraft lifting surfaces, i.e., wing, operating close to the ground (ground effect), is not well understood. In this work, the aerodynamic performance of a National Advisory Committee for Aeronautics (NACA) 4412 wing in ground effect equipped with MVGs is numerically investigated. Installed at 10% or 25% chord of the wing, the MVGs are arranged in a row in a counter-rotating pattern. The analysis is carried out at 18°angle of attack, which is close to the stall angle of attack of the wing. Four different cases of h/b = 0.1, 0.5, 1, and free flight (no ground effect) are considered in this analysis. The Reynolds number based on the wing chord is around 3 million. In this work, the detached eddy simulation (DES) method is employed to accurately capture the high energy levels of the vortex formed behind the MVGs, the wing tip vortex, and their contact with the ground. The DES simulations accurately depict the intricate flow dynamics of the NACA 4412 wing, and the use of MVGs enhances its performance while in close proximity to the ground. A negative Cp peak at the leading edge of the wing increases as it approaches the ground, according to the analysis. For h/b = 0.1, the lower wing over pressure is much higher than for other cases. The Q-criterion shows flow unsteadiness and wing tip vortex evolution. The flow region's vortical structures increase as the wing descends. The flow has the most coherent vortical forms at 0.1 aspect ratio. The ground effect leads to an increase in lift and a decrease in drag as the wing gets closer to the ground.

On Wing Tip Flow Around a Low Aspect Ratio Wing at Low Flight Speeds Using OpenFOAM® and Parallel Processing

On Wing Tip Flow Around a Low Aspect Ratio Wing at Low Flight Speeds Using OpenFOAM® and Parallel Processing

Wing Morphology and Echolocation of Rhinopoma hardwickii (Lesser Mouse-tailed Bat, Gray, 1831)

Rhinopoma hardwickii is currently classified as a member of the Yinpterochiroptera suborder, which includes frugivorous and some insectivorous bats. This species is the smallest in the Rhinopomatidae family and easily identified by its long tail. The wing morphology and echolocation calls of this species were studies to see if there were any changes in wing morphology between sexes, echolocation calls across different environments such as natural (roost and field) and controlled (captive), as well as different geographical areas. In this study, a total of 41 individuals (27 male and 14 female) of R. hardwickii were captured and their wing morphology was measured. The results show that there were no statistically significant variations in their morphometric characteristics or in wing morphology between the sexes. This species has with high wing loading and a high aspect ratio, as well as pointed wing tips. The echolocation calls consisted up to five harmonics of FM and CF- FM sweeps. Peak frequencies, start frequency, end frequency, and IPI of three separate environment parameters (roost, capitative, and field recording) differed significantly (p > 0.001).Moreover, we compared the frequency at maximum energy with four different geographical regions such as Kerala, Gujrat, and Israel to current study, and found that the frequencies of bat calls do not vary with geographical region (H=0.667, df=3, p=0.881). Therefore, the current study provides accurate identification of R. hardwickii on the basis of echolocation call in a different environment. The echolocation call and wing morphology data clearly show that this species is a fast flyer with limited manoeuvrability that feeds on forest canopy or over water bodies.

Analysing the Aerodynamic Performance of Dragonfly-Inspired Wing in Forward Flight: A Computational Approach

This paper presents a numerical investigation into the forward flight dynamics of a dragonfly-inspired wing. A three-dimensional (3-D) profiled wing model, specifically the right hind wing, was utilized for simulations. The wing model featured a tapering thickness from the wing root to the wing tip and from the leading edge to the trailing edge, replicating the morphological characteristics observed in dragonfly wings. Morphological data were acquired using a digital micrometre instrument, DSLR camera and Scanning Electron Microscope. The study aimed to evaluate the impact of advance ratio on the aerodynamic performance of the dragonfly-inspired wing during forward flight. Analysis was conducted on a single-degree-of-freedom flapping mechanism, with a flapping frequency set at 36 Hz to mimic the natural wingbeat frequency of a dragonfly. Results revealed a notable pressure disparity between the upper and lower surfaces during the downstroke, indicative of substantial lift generation during flapping motion. Additionally, the visualization of the leading-edge vortex formation provided further insights into the aerodynamic mechanisms at play. Overall, this study contributes valuable insights into the aerodynamic performance of insect-scale flapping wing micro air vehicles, offering potential advancements in their design and development

Regional Passenger Aircraft Type of An-158 with a Hybrid Propulsion Parametric Concept

ABSTRACT This study proposes a concept for the design and development of a modification of the An-158 regional passenger aircraft equipped with a hybrid propulsion system. The propulsion configuration includes two turboprop engines and two electric engines, with multidirectional propellers positioned symmetrically at the wing tips. This innovative design reduces wingtip vortices, decreasing inductive drag and improving aerodynamic efficiency. Parametric analyses were conducted using the modular software systems “Integration 2.1” and “Propeller 2.2” for typical flight profiles of the An-158. Despite the added weight from hybrid components, the modified aircraft design demonstrated reduced fuel consumption and harmful emissions in taxiing, takeoff, and climb modes. These findings highlight the potential of hybrid propulsion to enhance environmental performance while maintaining operational efficiency.

A method to optimal design the geometric parameters of a foldable flapping wing based on quasi-steady aerodynamics

Compared to rotorcraft and fixed-wing aircraft, foldable flapping wing aircraft have more significant advantages. Most foldable flapping wing aircraft (FFWA) are designed based on bionics of birds directly. However, the geometric parameters of these aircraft have been analyzed or optimized to improve a FFWA’s flight performance rarely. To improve FFWA’s flight performance and reduce the dependence on the thrust, a method to optimal design a foldable flapping wing geometric parameters based on aerodynamics has been proposed in this paper. First, a quasi-steady lifting line theory of foldable flapping wings was derived, and the expression of its lift in the vertical direction was obtained based on aerodynamics. Then, a typical FFWA model was taken as the studied object and an objective function to obtain the maximum lift in the vertical direction of a cycle was put forward. Third, we analyzed the relationship of some key geometrical parameters of the inner and outer wings of the FFWA model in terms of the requirements and capabilities of the objective function. Finally, we optimized the key geometrical parameters by using genetic algorithm. The angle between inner wings decreased from 132.58° to 16.59° and the angle between the inner wing and the outer wing decreased from 105.60° to 29.56° at the highest position, which were more similar to the flight status of birds. The outer wings were expanded more rapidly and the movement range of the outer wing tip was wider after optimization. The lift of the optimized aircraft increased with 110% by calculation.

Enhancing tip vortices to improve the lift production through shear layers in flapping-wing flow control

Flow control of a low-aspect-ratio flat-plate heaving wing at an average angle of attack of $10^{\circ }$ by a steady-blowing jet is numerically studied by using a feedback immersed boundary–lattice Boltzmann method. Blowing jets at the leading edge, mid-chord and trailing edge are considered. The wing enjoys the highest lift production with the trailing-edge downstream blowing jet, which improves the average lift by 50.0 % at $Re = 1000$ and 22.9 % at $Re = 5000$ through the enhancement of the tip vortex circulation caused by the increase in the mass flux of the shear layer at the wing tips. This increase in mass flux decreases as $Re$ increases from 1000 to 5000 due to its self-limiting mechanism. A mid-chord vertical blowing jet induces a middle vortex which enhances the lift production but the enhancement is smaller than that of trailing-edge downstream blowing jet. Other jet arrangements do not significantly increase the lift coefficient, but the mid-chord upstream blowing jet experiences a significant reduction in the drag coefficient, leading to an increase of 50.6 % in the average lift-to-drag ratio. The effectiveness of the flow control is not significantly affected by the aspect ratio.

A Comparative Analysis of Active Control vs. Folding Wing Tip Technologies for Gust Load Alleviation

As part of the Ultra High Aspect Ratio Wing Advanced Research and Designs (U-HARWARD) project, funded by CS2JU, various gust load alleviation (GLA) technologies have been developed and studied. GLA plays a crucial role in the development of new generation ultra-high aspect ratio wings (UHARWs), as it reduces gust loads, thereby decreasing the structural weight of the wing and, consequently, the entire aircraft. This weight reduction enhances overall aircraft efficiency, enabling a higher aspect ratio. GLA technologies are categorized into passive systems, which require no active intervention, and active systems, where control surfaces redistribute the aerodynamic loads. In this study, passive GLA was implemented using a folding wing tip (FWT) developed by the University of Bristol, while active GLA employed a Static Output Feedback controller developed by Politecnico di Milano. Both approaches were compared against a baseline aircraft configuration. A flutter assessment confirmed that FWT does not introduce aeroelastic instabilities, ensuring the aircraft remains flutter-free across its flight envelope. A thorough comparison of load envelopes, based on nearly 2000 load cases across different flight points and mass configurations, was conducted in compliance with CS25 regulations, examining both positive and negative gust conditions. The results show a possible 15% reduction in the dynamic load envelope for both passive and active solutions. Using NeOPT, a hybrid finite element (FE) model was developed, with a detailed global FEM (GFEM) for the wingbox and stick elements for other components. Linear gust analyses in Nastran, with the hinge locked and released, provided high-fidelity results, comparing wing failure indexes and demonstrating the effectiveness of the FWT solution.

Implementation of reengineering technology in the technological preparation for general aviation airplane wing tip manufacturing based on the construction of a digital mock-up

The object of this study is the technological preparation of the production of a light aircraft wing using reverse engineering technology. The subject of research is a quality indicator – the geometric accuracy of manufacturing the convex-concave parts of aerospace technology. Calculations of geometric accuracy were performed for the program-instrumental method of co-ordination. As the experimental part it was taken the worn out wing tip of a light aircraft. The following results were obtained. An approach for specifying the aerodynamic airfoil and cross sections of the wing tip when constructing its digital model has been proposed. A 3D scanning of the wing tip with the formation of a digital portrait in STL format, as well as its refinement into a STEP format, using organic and mechanical methods, was accomplished. A digital mock-up of the wing tip was built taking into account the geometry of the aerodynamic airfoil in cross sections as well as a digital mock-up of the form (mould) for its manufacture according to the polygonal model, which was created by the organic method due to it had the highest dimensional accuracy. It was determined that the maximum deviation of the actual wing contour from the theoretical one was as follows: the upper deviation was 0.84 mm, the lower deviation was –0.65 mm. The maximum deviation of the actual wing contour from the theoretical one was ±0.3 mm. The expected (calculated) errors did not exceed the specified value of the tolerance on the wing outer contour that equal to ±1.0 mm, thus, the adopted method of assembling the wing under the conditions of co-ordination by the program-instrumental method ensured the specified geometric accuracy. The results of experimental studies confirmed the adequacy of the proposed approach for determining the aerodynamic airfoil of the cross-sections of the digital mock-up of convex-concave parts for aerospace technology during their technological preparation for production with the use of reverse engineering.

Larval growth rate is not a major determinant of adult wing shape and eyespot size in the seasonally polyphenic butterfly Melanitis leda.

Insects often show adaptive phenotypic plasticity where environmental cues during early stages are used to produce a phenotype that matches the environment experienced by adults. Many tropical satyrine butterflies (Nymphalidae: Satyrinae) are seasonally polyphenic and produce distinct wet- and dry-season form adults, providing tight environment-phenotype matching in seasonal environments. In studied Mycalesina butterflies, dry-season forms can be induced in the laboratory by growing larvae at low temperatures or on poor food quality. Since both these factors also tend to reduce larval growth rate, larval growth rate may be an internal cue that translates the environmental cues into the expression of phenotypes. If this is the case, we predict that slower-growing larvae would be more likely to develop a dry-season phenotype. We performed the first experimental study on seasonal polyphenism of a butterfly in the tribe Melanitini. We measured both larval growth rate and adult phenotype (eyespot size and wing shape) of common evening brown butterflies (Melanitis leda), reared at various temperatures and on various host-plant species. We constructed provisional reaction norms, and tested the hypothesis that growth rate mediates between external cues and adult phenotype. Reaction norms were similar to those found in Mycalesina butterflies. We found that both among and within treatments, larvae with lower growth rates (low temperature, particular host plants) were more likely to develop dry-season phenotypes (small eyespots, falcate wing tips). However, among temperature treatments, similar growth rates could lead to very different wing phenotypes, and within treatments the relationships were weak. Moreover, males and females responded differently, and eyespot size and wing shape were not strongly correlated with each other. Overall, larval growth rate seems to be weakly related to eyespot size and wing shape, indicating that seasonal plasticity in M. leda is primarily mediated by other mechanisms.

Sensitivity of flows over three-dimensional swept wings at low Reynolds number

High angle of attack flows over swept three-dimensional wings based on the NACA 0015 profile are studied numerically at low Reynolds numbers. Linear stability analysis is used to compute instability and receptivity of the flow via the respective three-dimensional (triglobal) direct and adjoint eigenmodes. The magnitude of the adjoint eigenvectors is used to identify regions of maximum flow receptivity to momentum forcing. It is found that such regions are located above the primary three-dimensional separation line, their spanwise position varying with wing sweep. The wavemaker region corresponding to the leading global eigenmode is computed and found to lie inside the laminar separation bubble (LSB) at the spanwise location of peak recirculation. Increasing the Reynolds number leads to the wavemaker becoming more compact in the spanwise direction, and concentrated in the top and bottom shear layers of the LSB. As sweep is introduced, the wavemaker moves towards the wing tip, following the spanwise displacement of maximum recirculation. Flow modifications resulting from application of different types of forcing are studied by direct numerical simulation initialised with insights gained from stability analysis. Periodic forcing at the regions of maximum receptivity to momentum forcing results in greater departure from the baseline case compared to same (low, linear) amplitude forcing applied elsewhere, underlining the potential of linear stability analysis to identify optimal regions for actuator positioning.

Optimizing Winglet Cant Angle for Enhanced Aircraft Wing Performance Using CFD Simulation and Hybrid ANN‐GA

ABSTRACTWinglets are an extended angled or vertical projected at the wing tips used to reduce the drag encountered during the flight of an aircraft. The main aim of this research was to study the effects of winglets on NACA 4412 airfoil at 15° angle of attack. The simulation was done on the basis of the aerodynamic properties such as lift (CL), drag (CD), and lift/drag (CL/CD) ratio for both with and without the winglets at various cant angles. The designing was carried out in ANSYS Design Modeler for both with and without winglet. Further, the meshing part was again carried out in ANSYS Mesh. K‐Epsilon (two equation) turbulence model is used for the simulation at the inlet speed of 100 m/s, since it is the most common model used to simulate the mean flow characteristics for high turbulent conditions. Further, the cant angle has been optimized to get the maximum coefficient of lift using Nelder Mead, Genetic Algorithm, and Genetic Algorithm with ANN optimization techniques.

Spontaneous Wing Tip Edema in Captive Birds of Prey: Review of 41 Cases in the United Kingdom (2004-2022).

There is limited literature regarding wing tip edema (WTE) in raptors, and much of our current understanding of the condition is based on anecdotal reports. The aims of this retrospective study were to describe the clinical features of WTE in birds of prey, to identify prognostic factors for return to flight and patient survival following diagnosis, and to develop and assess the clinical significance of a novel WTE grading system. Between 2004 and 2022, 41 cases of WTE were identified in 39 captive birds. No cases were found in wild birds. Harris's hawks (Parabuteo unicinctus), lanner falcons (Falco biarmicus), and peregrine falcons (Falco peregrinus) had the highest frequencies of WTE, and all cases presented between October and May. Increasing days of air frost per month and colder median monthly temperatures were significant risk factors for the development of WTE. Of the cases where patient outcomes were known, 23/31 (74.2%) cases returned to normal flight and 29/34 (85.3%) cases survived. End-stage disease, represented by primary flight feather loss and metacarpal ischemic (dry) gangrene, and enalapril use were associated with poor patient outcomes. Presentation within 24 hours of disease onset, isoxsuprine use, and physiotherapy were associated with improved patient outcomes. This study showed that WTE is an infrequently encountered but clinically significant condition in captive raptors and is associated with an overall high morbidity and moderate mortality risk.